In an ultrasonic welding process, adjacent surfaces of a clamped work piece are joined together by the controlled application of vibration energy to the work piece. Transmission of vibration energy creates surface friction and heat along interfacing surfaces of the work piece. The heat softens the materials of the interfacing surfaces which ultimately bonds the surfaces together, thus forming a welded joint or weld spot.
A typical ultrasonic welding system includes various interconnected welding tools. Primary among these tools are a vibrating sonotrode/welding horn and an anvil assembly. The anvil assembly may include an anvil body and a rigid back plate, the latter of which is bolted to a support member such as a frame, beam, or robot. The work piece is clamped between the horn and the anvil body. The welding horn vibrates at a calibrated frequency in response to an input signal. The anvil body acts as a reaction surface to the vibrating horn.